Active monsoon pattern this week; drought intensifies in California

Filed in Uncategorized by on July 20, 2013 50 Comments

The prevailing pattern over California has been rather active thus far this summer, and that trend appears likely to continue for the foreseeable future. A very active summer monsoonal surge is ongoing over the Desert Southwest this weekend, with intense thunderstorms and significant flash flooding taking place in parts of Arizona, New Mexico, and Nevada.

GOES water vapor imagery, American Southwest (NRL).

GOES water vapor imagery, American Southwest (NRL).

A rather large mesoscale convective system (MCS) that developed late yesterday over Arizona propagated westward over Southern California earlier today, triggering more thunderstorms over inland areas and bringing some showers as far west as the coastal areas in Los Angeles County. While that old MCC has since dissipated and moved out over the Pacific Ocean, a new and even more impressive MCS has developed over Arizona this evening and is moving westward once again. Also prominent in water vapor imagery is a weak cut-off low centered near the international border near Baja California. The combination of this westward-propagating MCS and the prevailing easterly flow of monsoonal moisture around the northern periphery of the low will bring extensive cloudiness and occasional shower activity to much of SoCal over the next day or so, with occasional thunderstorm activity when subtle triggering mechanisms move through. This moisture will very slowly move northward over the next 72 hours and will bring widespread mountain thunderstorm activity in NorCal. There is some possibility, given the very moist air and the presence of a couple of weak upper-level waves, that a few showers or thunderstorms could occur in NorCal by Wednesday as well, though chances are certainly higher south of the Monterey Bay Area. This active monsoonal pattern will certainly be worth watching over the next few days.

U.S. Drought Monitor (NOAA/NDMC)

U.S. Drought Monitor (NOAA/NDMC)

Also worth mentioning at this time is the current state of drought in the Golden State. Most of you are acutely aware that the January-May 2013 period was the driest such period on record in most parts of California, and that season totals were significantly below average nearly everywhere. The extremely dry second half of the rainy season was offset somewhat by an extremely wet November-December in 2012, but since this dry year comes on the heels of another dry year last rainy season, we’re starting to experience some pretty significant impacts from the present multi-year dry spell. The most recent Drought Monitor classification places nearly the entire state under “severe drought” conditions, which is a significant increase in intensity and extent since the last evaluation. California is on the western periphery of a very extensive region of drought that extends from the lower Mississippi Valley in the southeast to the Northern Rockies in the northwest, including a large region of extreme to exceptional drought in the western Great Plains and Southern Rockies. While it’s too early to say how these drought conditions might change once the new rainy season begins late in Fall 2013, it’s pretty clearly going to take a lot of water to make up for some of the large deficits that have accumulated over the past few years.

© 2013 WEATHER WEST

One Pingback/Trackback

  • Shady Blues

    Las Vegas is getting hammered again…

    • http://weatherwest.com Daniel Swain

      Yes, indeed. Some very impressive cells over the Las Vegas Valley tonight…and all of that remnant moisture will get advected over CA tomorrow.

  • redlands

    redlands on July 20, 2013 at 11:16 pm said:

    Redlands, Ca around 12 noon- ish July 20, 2013 received 0.23 of rain — with a high rain-rate of 0.76 — hi dew point of 74 — which is considered oppressive according to the tv news man

    • http://weatherwest.com Daniel Swain

      A dewpoint of 74 is rather high even for the Gulf Coast in summertime, so that’s saying something! Hopefully the air temperature wasn’t much higher than that, though, so it probably wasn’t too uncomfortable. Just an indicator of the extremely moist airmass moving overhead…

      • redlands

        Daniel — Redlands, Ca hi for July 20th 2013 was reached at 451pm — we got up to 87 — rain started round noonish — didnt last that long — bout a hour —- clouds cleared out fast —- the high heat index was 92 at 449pm —- highest humidity was at 222pm at 92% — was muggy —– i was really suprised that we got any rain — with only a 20% chance —- on the radar it showed a small cell that popped up — Redlands Ca was lucky to get rain — I dont know if all parts of Redlands, Ca received any rain

  • Dan the Weatherman

    I picked up .03″ of rain here in Orange this afternoon when it rained for almost an hour. The temperature was very pleasant all day today being mostly in the 70s despite the high humidity. It was actually in the low-mid 70s this afternoon when it was raining and it didn’t have a chance to warm up again even with the sun coming out in the very late afternoon for a while before sunset.

    The radar is certainly showing an impressive area of showers and thunderstorms in the deserts from about the San Bernardino Mountains extending all the way to the Nevada border and appears to be moving toward the Inland Empire and possibly even Orange County. I sure hope these hold together and bring some rare significant rains west of the mountains this morning and afternoon!

  • kcanton40

    Hi Dan,

    So, this time does it look like this new moonsonal moisture surge will make it all the way up here in Napa, Ca? Does it look like the high pressure system is centered in the right position for us to see some activity as far as thundershowers over the next couple of days because we are west of the Sierra Mountain range.

    • http://weatherwest.com Daniel Swain

      There is a chance that the Bay Area could see some activity over the next 72 hours. Best chance would be tomorrow evening though Tuesday evening. Not a slam dunk by any means, but I think there’s a reasonable shot. Definitely expect some interesting skies over the next couple of days!

  • http://weatherwest.com Daniel Swain

    There’s some nice nocturnal convection developing right now across much of central and southern California…

  • Shady Blues

    As expected most of the coastal and valley areas of southern California did not get much in the way of thunderstorms….mainly just sporadic showers. Although I did see some very nice build ups off the mountains today.

    Can’t wait until this Fall and Winter. Really looking forward to the storms…especially the strong storms….

    • Dan the Weatherman

      I am afraid we are not going to have a good winter until we get out of this combination of -PDO, +AMO, and weak ENSO/ neutral ENSO. I still have not seen signs that we are out of this general regime yet, but one thing that HAS been different this year than in the last couple of years is that the SSTs are warmer off Baja California and the Socal coast this summer than they have been lately.

  • kcanton40

    Yikes!! We cannot afford another bone dry year and the general pattern above does not give good odds. However, I think it is way to early to tell at this point. Is there any chance that any one of those combinations can flip between now and then and is there still time for that to happen? Also, what about the QBO(stratospheric wind pattern blowing from west to east) because it goes into its negative and positive phases too. What would it take for the general pattern to break so we can get a solid winter here in California? We are going to need a ton of water starting during the Fall, Winter and Spring. All we can do is hope and keep our fingers cross for the upcoming rainy season for the state. Also, here in the Bay Area we did not get much convective activity this time around can you tell when might get the next moonsonal surge for the state in the future or this is it for awhile?

    • Dan the Weatherman

      The PDO and AMO modes tend to stay put for quite a while, for a couple of decades or so, but that doesn’t mean that they could temporarily shift at times. I had thought that the PDO had turned positive this summer, but found out that wasn’t the case. ENSO is still neutral, but could turn into at least a weak La Nina if the tropical Pacific SSTs continue to cool, but could easily remain neutral as well. I do think this next winter will be wetter in most of CA than this last winter, which was pitiful to say the least, but I don’t think it will be above normal, but will probably average somewhat closer to normal, as opposed to WAY below normal. What we really need is a significant El Nino event to shake things up and bring a wetter winter for a change. I am not as familiar with the QBO effects, so I am not sure how the switch in the QBO will affect the current weather regime. Maybe someone else on this blog will be able to offer a bit more insight into that. I had thought that a Westerly QBO often led to a wet fall and a somewhat drier winter for at least Socal, but that has been the case over the last several years despite Easterly and Westerly QBOs.

      • Dan the Weatherman

        I don’t see any major monsoonal surges in the near future except for a more minor surge tomorrow and into Friday for interior Socal, but as high pressure builds west once again later next week, that could potentially lead to another monsoon event. The NWS isn’t forecasting that to happen as of now, but we will just have to wait and see.

  • redlands

    Redlands California Update : July-20 – 2013 – 0.20 July-21- 2013 – 0.06 — for a monthly total of 0.26 of rain for July 2013 — Average rainfall for July is 0.10

    Wettest July
    1) 0.66 – July -1984
    2) 0.60 – July – 1992
    3) 0.35 – July – 2012
    4) 0.33 – July -2011
    5) 0.29 – July-1986
    6) 0.26 – July – 2013 – still active
    Records since July 1982 —- Some interesting facts — July 2013 has received more rain than last years 2012-2013 rain season – for example

    0.13 – April -2013
    0.21 – May-2013
    0.00 – Septemember 2012
    0.00- October – 2012 —- just shows how dry its been

    I’ve recorded 32 Julys and 14 of them have been bone dry with 0.00 — 24 of them i have recorded between 0.00-0.10 of rain.

    • sc100

      It’s interesting how the last three years have been so strong. Now we just need records like that in the winter.

  • Nicholas

    Me and a friend went storm chasing on Monday. We saw a few lightning strikes near Phelan, CA in the early afternoon. Then we went to Barstow and core punched that severe thunderstorm. We got there when the thunderstorm was in its mature stage and because of that didn’t see any lightning but we got heavy rain and wind. Then on the way home we saw that huge cell on the way home that was near Little Rock. We should have pulled over and looked at it as it was still growing but for some reason we went home.

    • Shady Blues

      That must of been a awesome experience. In socal, chasing is one of the only ways you can guarantee yourself a thunderstorm…its really unfortunate.

      • Nicholas

        So Cal storm chasing would be a lot better but there are a few reasons its not idle.

        + California has the second highest gas prices in the nation only to Hawaii.

        + Lack of any real roads once you get out to the high and low desert. You don’t want to get stuck on a dirt road so you better hope something hits or gets near the 15.

        +Lack of data coverage in the desert.

        + Heavy Traffic.

        + Sand that kills visibility if inflow/outflow winds kick up

        The best thing to do is chase an MCS at night time as it goes through the desert. Ones with little precip and lots of high based lightning.

  • http://weatherwest.com Daniel Swain

    SoCal might see some more elevated convective activity over the next 24 hours as the upper low off the coast is drawing in a bit more mid-level moisture than previously expected. Don’t think it will make it up to the Bay Area, but worth keeping an eye on…

  • Nicholas

    So Cal is already getting some showers at the beaches and valleys.

    • Shady Blues

      To be honest, its looking more impressive than the last event…did you get lighting with the cell over Whittier?

      • Dan the Weatherman

        I am seeing some lightning to my NW from here in Orange. Nicholas, are you seeing the lightning right now or are you in bed for the night?

        • Nicholas

          As soon as I went to bed things exploded. I chose the wrong time to go to bed. Dad saw lightning and we got a heavy burst of rain.

  • Shady Blues

    Just saw a brilliant flash of lighting…things are starting to get interesting!

    • Shady Blues

      Thunderstorms are developing over the coastal/valley areas? This is extremely rare indeed!

      • Dan the Weatherman

        There must be an easterly wave passing through the area aiding in the convection or it is the result of the low pressure north of the Gulf of California (as described in tonight’s NWS AFD).

  • Nicholas

    Here is a graphic over the past 10 years for Southern California lightning. What your chances are of seeing lightning.

    Notice how the Whittier/Diamond Bar area have one of the highest chances west of the mountains.

    https://sphotos-a-lax.xx.fbcdn.net/hphotos-frc3/1044196_628050357206964_852187733_n.png

  • http://weatherwest.com Daniel Swain

    On that note, an interesting resource:

    http://www.sos.noaa.gov/Datasets/dataset.php?id=6

    Coastal California is a pretty unique place (especially at our latitude) to have so few thunderstorms. It’s that cold California Current!

  • Shady Blues

    Dan,

    Check this forecast out for Winter:
    http://www.liveweatherblogs.com/index.php?option=com_community&view=groups&task=viewdiscussion&groupid=8&topicid=1122&Itemid=179

    I know long range forecasts are a crap shot, but there are some people who think we may have a very wet winter. I hope they are right.

    • Dan the Weatherman

      He is forecasting a weak to moderate El Nino later this year, which is the basis for his long range forecast. Right now, SSTs in the eastern tropical Pacific are somewhat below average and near average over and near the Date Line (180W), almost resembling weak La Nina conditions but not widespread enough. I currently don’t see any signs of El Nino developing at this time, however, there is a good deal of warm water in the sub-surface region from 120-125W westward and near normal elsewhere. The cold water is very shallow and limited to the far eastern Pacific. If only this warm water can be transported to the eastern tropical Pacific via a Kelvin Wave, then El Nino conditions could be possible. I would really like to see a good El Nino year as we really need to have a good winter after the last two being so bad in terms of dryness.

    • http://weatherwest.com Daniel Swain

      As Dan mentioned, there’s little sign of either El Nino or La Nina conditions at the moment. Eastern Tropical Pacific SSTs are below average at the moment but there’s a modest pool of warmer than average water in the subsurface region across much of the basin. Neither the dynamical nor the statistical models are projecting a meaningful ENSO signal for the upcoming winter, and these models now have some skill as we’re less than six months out. We still aren’t great at ENSO prediction, even on intra-annual timescales, but at this point I don’t think it’s particularly likely we’ll see meaningfully +/- ENSO conditions this winter.

      As far as the PDO is concerned: we’re still in the negative phase, unfortunately. The index did briefly head up to around neutral early in the summer, but keep in mind this is a decadal index and the signal is really only relevant on multi-year timescales. Unless there is some drastic change over the next few months, I think there’s still a pretty high chance that our winter will be influenced by negative PDO teleconnections: that is, a modest chance of below average precipitation.

      Ultimately, I see no basis at all for predicting above-average precipitation this winter.

  • Nicholas

    I tell you what this time of year most of the time I feel nasty getting up with no AC. The past few days its been rather pleasant being 30 miles inland in the late night early morning hours. Feels a bit more like early fall.

  • http://weatherwest.com Daniel Swain

    Some very interesting developments in the Pacific Ocean over the past few weeks. There are currently some very large (3C+) SST anomalies in the extratropical North Pacific, which are in fact record-breaking anomalies. It’s hard to say what has led to these anomalies, but if they persist there are most likely pretty strong teleconnections for West Coast conditions heading into fall and early winter (that is, a positive PNA-like response and possibly below normal precip). If these anomalies are very persistent or continue to intensify (as they have over the past two weeks), that probably does not bode well for a healthy wet season in CA this coming winter.

    However, there is currently an increasingly large pool of positive subsurface heat anomalies in the equatorial East Pacific. While the dynamical models are not presently projecting development of El Nino conditions in the coming months, this is something that should also be watched. Keep your eyes to the Pacific for the rest of summer!

  • kcanton40

    Hi Dan,

    I’m very encouraged about the upcoming winter. There is a couple of websites you and others may want to check out as for my basis for a wetter winter ahead, particularly DEC-Mar. Please visit mammothweather.com. Howard Schectner has been predicting winters for California for 30+ years and has taken into account SSTs, MJO, the phases of AO/NAO, especially the QBO(Quasi Biennial Oscilliation) or the winds in the stratosphere and has been fairly accurate every year of what type of winter we would have. Also, please take a look at the latest weather forecasting model on his blog from yesterday which currently predicting a very wet Dec-Feb for the state. I remember, this same model, while not perfect, but getting better, also predicted very wet conditions for last Dec and bone dry conditions for Jan-Mar 2013. He also has information on his site about the phases of the -AO/-NAO has a “non linear” affect on the west coast. He implies that we look at all of the teleconnection signs to predicting the upcoming winter. Also, he’s predicting that the rest of this month will continue to be dry, but we may get impacted by a dying tropical storm sometime next month with above normal temperatures which he briefly wrote in his blog about a week ago. Please let me know your thoughts?

    • Dan the Weatherman

      Kcanton40, thank you for the link to mammothweather.com. I have never been to that site before and I will add it to the list of many weather sites that I visit regularly. Another good site that I frequently visit and is very similar as far as winter storm discussion is concerned is Open Snow (http://opensnow.com/dailysnow/tahoe). The primary focus of Brian Allegretto’s discussions is doing forecasts both short and long range for ski resorts in the Tahoe region.

    • http://weatherwest.com Daniel Swain

      As much as I wish it were otherwise, I still don’t see any evidence of an increased likelihood of a wetter-than-usual winter in California. I just checked the CFS projections for winter 2013-2014, and those don’t seem to support a wetter or drier than usual season either (check out http://www.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst ).
      Long-lead intra-annual forecasting is still in its infancy, and unless there is a very strong teleconnection signal (i.e. a major El Nino event) it’s very difficult to make any sort of precip forecast for California that is likely to have even modest skill. Current North Pacific SSTs, if anything, suggest that the fall may well be drier than usual, but beyond that I don’t think anyone can say at this point.

  • kcanton40

    Dan,
    The specific name of the site model is called the CFSv2 Seasonal Climate Forecast which is predicting a wetter winter for the state(Dec-Feb) 2013-2014.

    • Dan the Weatherman

      I will certainly keep an eye on Howard’s predictions as well as the CFSv2 seasonal climate forecast, which comes from the Climate Prediction Center (CPC). I am really hoping for a better winter this year, but my hopes aren’t extremely high due to the +AMO, -PDO phase that we are currently stuck in especially if we wind up in ENSO neutral or weak ENSO territory. The change in the QBO could make a difference, but I am not knowledgeable enough of the effects of the QBO on varying oscillation patterns to make a good guess on that. To get my hopes higher at this point IMO, we need a strong El Nino, but a strong La Nina could benefit the northern Sierras as well, but that scenario could leave the far southern part of CA drier than average. A La Nina like 2010-11 would certainly be good at this point if that type of pattern could only repeat again.

    • http://weatherwest.com Daniel Swain

      As I mentioned above, I don’t see that the CFS is actually projecting greater-than-normal precip for CA this winter.

  • Nicholas

    The days are getting shorter. I have always noticed that the sun starts setting more early around the 3-4’th week of August. The average night time lows start dipping for most of the nation (except for the southwest). Summer tends to linger in California longer then most of the nation.

    With that being said October will tell us a lot about winter time in So Cal. Every time we get above average rain in October we have had above average winters in So Cal. The same for lower totals as well.

  • kcanton40

    Hi Dan,
    I’m still learning/researching how the QBO affects our weather, however, read the quote from Howard on his mammoth report website which makes a lot of sense to me and gives me a lot of hope for our state, only time will tell:
    “The big thing is that with the QBO in the westerly phase you will not have as strong of blocking over the Greenland and as strong a Hudson Bay Low. The cold air will be allowed to flush out over the Atlantic. When you have a persistent deep Hudson Bay low with downstream blocking it keeps the PNA strong in the positive mode as well. We want a negative PNA and a pattern that has a wavelength that is open across the us… I see more of that this winter. I think that we are all good for a nice winter..December through March”

    Howard

  • alan

    Since the monsoon all but disappeared from SoCal there’s nothin left but to watch the long range and see what ‘weather’ pops up first and if it lasts into the near range LOL

    Right now that means watching the movement of that (abnormally?) strong tropical storm, latest model run has it creeping up baja right along the coast……sometimes the most exciting weather in SoCal this time of year is a mythical long range GFS tropical storm having a direct hit to SoCal, yay.

  • kcanton40

    Another thing we are going to have to watch regarding El Nino for this upcoming winter is its strength. This mornings latest CFsv2 long range outlook seems to indicate at least a weak to possibly a moderate El Nino strength. We are indeed due for a strong El Nino pattern, which I’m not anticipating this winter, maybe during the winter of 2014-2015?

    • Dan the Weatherman

      That is IF we can get an El Nino to develop this year, which I am not sure is going to happen since I haven’t really seen any significant warming of the SSTs in the eastern Pacific as of yet. There is a lot of warm subsurface water, which has not managed to make it to the surface as of yet, but it certainly bears watching. I have a feeling that the -PDO is going to prevent any major El Nino event from forming this year, but a weaker one is at least a possibility.

  • http://weatherwest.com Daniel Swain

    Very active convective setup now appears likely for northern and central California this week. Will have a full update on thunderstorm potential and a drought/long range update by late tonight.

  • kcanton40

    Hi Daniel,

    The next several days could be very interesting up here in Napa/Nor Cal. Looking forward to thunderstorm potential and monitoring very closely the developing cut off low pressure system off our coast!!!

  • Nicholas

    Looks like everyone will have a chance of storms besides the coast and valleys of So Cal.

  • kcanton40

    Yes, the -PDO in the Pacific does hinder the development of strong El Nino formation which is why I believe we have not seen one since the Fall/Winter of 1997. I do know the phases can last 20-30yrs. I took a peek at Bryan Allegretto website which I added to my weather forecasting tools and he also saying that it is too early to get excited about the hopes of a good winter. As of recent, he does not like the current set of the SSTs of the Pacific which he says is similar to the last 2/3 of the winter of last year. He says he has predicted accurately the last 3yrs in a row around October of each of those years which I think is the best time to make such predictions. The CFSv2 is a climate model predictor(not a forecast) tool which will fluctuate in the coming months. I noticed that currently it has been predicting a very dry pattern for the state from Jan-Mar 2014. Howard from the mammoth website also says he will give his official prediction for winter sometime during the Fall. Lots of things can change and happen. I realize it is way too early to tell what this upcoming winter will be like. We will be watching all of the global tele-connection signs such as the position of the SSTs in the Pacific both along the coast/far western pacific, definitely the strength of the ENSO, the phase of the QBO(which has reversed late spring to the westerly phase compared to the last 2 yrs) the current phases of the -PDO, -NAO, the strengths of the MJO(Madden Julian Oscillation) later during the Fall/Winter, and the polar/southern jet streams.

  • Pingback: Monitoring California Hazards « Earth « Science Today